Method And System For Supporting A Variable And Energy Efficient Data Rate Using A Duty Cycling Technique And Multiple Power States On An Ethernet Link

ABSTRACT

Aspects of a method and system for supporting a variable and energy efficient data rate using a duty cycling technique and multiple power states on an Ethernet link are provided. In this regard, a data rate on a network link may be duty cycled based on characteristics of data communicated over it. The network link may operate at a first data rate for a first portion of the time interval and may operate at a second data rate for a second portion of the time interval. The duration of each portion of the time interval and/or the data rate during each portion of the time interval may be adjusted to control the duty cycling. Power consumed in a device connected to the network link may be controlled based on the duty cycling of the link.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This patent application makes reference to, claims priority to andclaims benefit from:

U.S. Provisional Patent Application Ser. No. 61/014,253 filed on Dec.17, 2007;

U.S. Provisional Patent Application Ser. No. 61/014,265 filed on Dec.17, 2007;

U.S. Provisional Patent Application Ser. No. 61/014,278 filed on Dec.17, 2007; and

U.S. Provisional Patent Application Ser. No. 61/014,293 filed on Dec.17, 2007.

This patent application also makes reference to:

U.S. patent application Ser. No. ______ (Attorney Docket No. 19268US01)filed on even date herewith;

U.S. patent application Ser. No. ______ (Attorney Docket No. 19270US01)filed on even date herewith; and

U.S. patent application Ser. No. ______ (Attorney Docket No. 19271US01)filed on even date herewith.

Each of the above stated applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to a method and system fornetworking. More specifically, certain embodiments of the inventionrelate to a method and system for supporting a variable and energyefficient data rate using a duty cycling technique and multiple powerstates on an Ethernet link.

BACKGROUND OF THE INVENTION

With the increasing popularity of electronics such as desktop computers,laptop computers, and handheld devices such as smart phones and PDA's,communication networks, and in particular Ethernet networks, arebecoming an increasingly popular means of exchanging data of varioustypes and sizes for a variety of applications. In this regard, Ethernetnetworks are increasingly being utilized to carry, for example, voice,data, and multimedia. Accordingly more and more devices are beingequipped to interface to Ethernet networks.

As the number of devices connected to data networks increases and higherdata rates are required, there is a growing need for new transmissiontechnologies which enable higher data rates. Conventionally, however,increased data rates often results in significant increases in powerconsumption. In this regard, as an increasing number of portable and/orhandheld devices are enabled for Ethernet communications, battery lifemay be a concern when communicating over Ethernet networks. Accordingly,ways of reducing power consumption when communicating over Ethernetnetworks may be needed.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for supporting a variable and energyefficient data rate using a duty cycling technique and multiple powerstates on an Ethernet link, substantially as shown in and/or describedin connection with at least one of the figures, as set forth morecompletely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an Ethernet connection betweentwo network nodes, in accordance with an embodiment of the invention.

FIG. 2 is a block diagram illustrating an exemplary Ethernet overtwisted pair PHY device architecture comprising a multi-rate capablephysical layer block, in accordance with an embodiment of the invention.

FIG. 3A is a diagram illustrating duty cycling a data rate of a networklink between a zero data rate and a maximum supported data rate of thelink, in accordance with an embodiment of the invention.

FIG. 3B is a diagram illustrating duty cycling a data rate of a networklink between a zero data rate and an intermediate supported data rate ofthe link, in accordance with an embodiment of the invention.

FIG. 3C is a diagram illustrating duty cycling a data rate of a networklink between a first intermediate supported data rate of the link and asecond intermediate supported data rate of the link, in accordance withan embodiment of the invention.

FIG. 3D is a diagram illustrating duty cycling a data rate of a networklink between an intermediate supported data rate of the link and amaximum supported data rate of the link, in accordance with anembodiment of the invention.

FIG. 3E is a diagram illustrating duty cycling a data rate of a networklink which carries traffic with varying latency sensitivities, inaccordance with an embodiment of the invention.

FIG. 4 is a flow chart illustrating exemplary steps for duty cycling adata rate of a network link, in accordance with an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor supporting a variable and energy efficient data rate using a dutycycling technique and multiple power states on an Ethernet link. Incertain embodiments of the invention, a network link may be duty cycledbased on characteristics of data communicated over it such that data maybe communicated over the link at a first data rate for a first portionof a specified time interval and may be communicated over the link at asecond data rate for a second portion of the specified time interval.The duration of each portion of the time interval and/or the data rateduring each portion of the time interval may be adjusted to control theduty cycling. The characteristics may comprise an amount of, a type of,and/or an application associated with, the data communicated over thenetwork. The first data rate may be a zero data rate and the second datarate may be a maximum data rate that may be supported by the networklink. The data rate may be controlled by adjusting a number of activephysical channels in the network link, a signal constellation utilizedfor representing data on the network link, a number of pulse amplitudemodulation levels utilized for signaling on the network link, and/or oneor more inter-frame gaps on the network link. Power consumed in a deviceconnected to the network link may be controlled based on the dutycycling of the link. In this regard, components in the device may bepowered down during the first portion of the time interval.

FIG. 1 is a block diagram illustrating an Ethernet connection betweentwo network nodes, in accordance with an embodiment of the invention.Referring to FIG. 1, there is shown a network 100 that comprises networknodes 102 and 104. Notwithstanding the embodiment depicted in FIG. 1,aspects of the invention may be utilized in networks of any size,topology, and/or technology. The nodes 102 and 104 may communicate via alink 112. The link 112 may comprise up to four or more physicalchannels, each of which may, for example, comprise an unshielded twistedpair (UTP). The nodes 102 and 104 may communicate via two or morephysical channels comprising the link 112. For example, Ethernet overtwisted pair standards 10BASE-T and 100BASE-TX may utilize two pairs ofUTP while Ethernet over twisted pair standards 1000BASE-T and 10GBASE-Tmay utilize four pairs of UTP. In this regard, however, aspects of theinvention may enable varying the number of physical channels via whichdata is communicated.

In an exemplary embodiment of the invention, the nodes 102 and/or 104may comprise a twisted pair PHY capable of operating at one or morestandard rates such as 10 Mbps, 100 Mbps, 1 Gbps, and 10 Gbps (10BASE-T,100GBASE-TX, 1GBASE-T, and/or 10GBASE-T); potentially standardized ratessuch as 40 Gbps and 100 Gbps; and/or non-standard rates such as 2.5 Gbpsand 5 Gbps.

In an exemplary embodiment of the invention, the nodes 102 and/or 104may comprise a backplane PHY capable of operating at one or morestandard rates such as 10 Gbps (10GBASE-KX4 and/or 10GBASE-KR); and/ornon-standard rates such as 2.5 Gbps and 5 Gbps.

In an exemplary embodiment of the invention, the nodes 102 and/or 104may comprise an optical PHY capable of operating at one or more standardrates such as 10 Mbps, 100 Mbps, 1 Gbps, and 10 Gbps; potentiallystandardized rates such as 40 Gbps and 100 Gbps; and/or non-standardizedrates such as 2.5 Gbps and 5 Gbps. In this regard, the optical PHY maybe a passive optical network (PON) PHY.

In addition, the link partners, node 102 and/or 104 may supportmulti-lane topologies such as 40 Gbps CR4, ER4, KR4; 100 Gbps CR10, SR10and/or 10 Gbps LX4 and CX4. Also, serial electrical and copper singlechannel technologies such as KX, KR, SR, LR, LRM, SX, LX, CX, BX10, LX10may be supported. Non standard speeds and non-standard technologies, forexample, single channel, two channel or four channels may also besupported. More over, TDM technologies such as PON at various speeds maybe supported by the link partner nodes 102 and/or 104.

The node 102 may comprise a host 106 a, a medium access control (MAC)controller 108 a, and a PHY device 104 a. The node 104 may comprise ahost 106 b, a MAC controller 108 b, and a PHY device 110 b.Notwithstanding, the invention is not limited in this regard. The nodes102 and 104 may each comprise at least one network port which may enablethe nodes 102 and 104 to communicate via the link 112. In this regard,each network port may comprise suitable logic, circuitry, and/or codeoperable to enable transmission and/or reception of data over acorresponding network link, such as the link 112. In the network nodes102 and 104, components of one or more network ports may reside in oneor more of the host 106, the media access controller 108, and the PHYdevice 110. Moreover, various components of a network node may beassociated with a single port or may be associated with a plurality ofports. Notwithstanding the embodiment depicted in FIG. 1, each of thenodes 102 and 104 may comprise a plurality of ports enabled tocommunicate over a corresponding plurality of links.

In various embodiments of the invention, the node 102 and/or 104 maycomprise, for example, networking devices such as personal computers,handheld devices, servers, switches, routers, and bridges. In variousembodiments of the invention, the node 102 and/or 104 may comprise, forexample, A/V equipment such as microphones, instruments, sound boards,sound cards, video cameras, media players, graphics cards, or otheraudio and/or video devices. Additionally, the nodes 102 and 104 may beenabled to utilize Audio/Video Bridging and/or Audio/video bridgingextensions (collectively referred to herein as audio video bridging orAVB) for the exchange of multimedia content and associated controland/or auxiliary data.

The PHY devices 110 a and 110 b may each comprise suitable logic,circuitry, and/or code that may enable communication, for example,transmission and reception of data, between the node 102 and the node104. The PHY devices 110 a and 110 b may support, for example, Ethernetover copper, Ethernet over fiber, and/or backplane Ethernet operations.The PHY devices 110 a and 110 b may enable multi-rate communications,such as 10 Mbps, 100 Mbps, 1000 Mbps (or 1 Gbps), 2.5 Gbps, 4 Gbps, 10Gbps, or 40 Gbps, for example. In this regard, the PHY devices 110 a and110 b may support standard-based data rates and/or non-standard datarates. Moreover, the PHY devices 110 a and 110 b may support standardEthernet link lengths or ranges of operation and/or extended ranges ofoperation. The PHY devices 110 a and 110 b may enable communicationbetween the node 102 and the node 104 by utilizing a link discoverysignaling (LDS) operation that enables detection of active operations inthe other node. In this regard the LDS operation may be configured forsupporting a standard Ethernet operation and/or an extended rangeEthernet operation. The PHY devices 110 a and 110 b may also supportautonegotiation for identifying and selecting communication parameterssuch as speed and duplex mode.

In various embodiments of the invention, the PHY devices 110 a and 110 bmay comprise suitable logic, circuitry, and/or code that may enabletransmission and/or reception utilizing a first duty cycling scheme inone direction and transmission and/or reception utilizing a second dutycycling scheme in the other direction. For example, the data rates andduty cycle period in one direction may be different from the data ratesand duty cycle period in the other direction.

The data transmitted and/or received by the PHY devices 110 a and 110 bmay be formatted in accordance with the well-known OSI protocolstandard. The OSI model partitions operability and functionality intoseven distinct and hierarchical layers. Generally, each layer in the OSImodel is structured so that it may provide a service to the immediatelyhigher interfacing layer. For example, layer 1, or physical layer, mayprovide services to layer 2 and layer 2 may provide services to layer 3.The data transmitted may comprise frames of Ethernet media independentinterface (MII) data which may be delimited by start of stream and endof stream delimiters, for example.

In an exemplary embodiment of the invention illustrated in FIG, 1, thehosts 106 a and 106 b may represent layer 3 and above, the MACcontrollers 108 a and 108 b may represent layer 2 and above and the PHYdevices 110 a and 110 b may represent the operability and/orfunctionality of layer 1 or the physical layer. In this regard, the PHYdevices 110 a and 110 b may be referred to as Physical layertransmitters and/or receivers, physical layer transceivers, PHYtransceivers, PHYceivers, or PHY, for example. The hosts 106 a and 106 bmay comprise suitable logic, circuitry, and/or code that may enableoperability and/or functionality of the five highest functional layersfor data packets that are to be transmitted over the link 112. Sinceeach layer in the OSI model provides a service to the immediately higherinterfacing layer, the MAC controllers 108 a and 108 b may provide thenecessary services to the hosts 106 a and 106 b to ensure that packetsare suitably formatted and communicated to the PHY devices 110 a and 110b. During transmission, each layer may add its own header to the datapassed on from the interfacing layer above it. However, duringreception, a compatible device having a similar OSI stack may strip offthe headers as the message passes from the lower layers up to the higherlayers.

The PHY devices 110 a and 110 b may be configured to handle all thephysical layer requirements, which include, but are not limited to,packetization, data transfer and serialization/deserialization (SERDES),in instances where such an operation is required. Data packets receivedby the PHY devices 110 a and 110 b from MAC controllers 108 a and 108 b,respectively, may include data and header information for each of theabove six functional layers. The PHY devices 110 a and 110 b may beconfigured to encode data packets that are to be transmitted over thelink 112 and/or to decode data packets received from the link 112.

The MAC controller 108 a may comprise suitable logic, circuitry, and/orcode that may enable handling of data link layer, layer 2, operabilityand/or functionality in the node 102. Similarly, the MAC controller 108b may comprise suitable logic, circuitry, and/or code that may enablehandling of layer 2 operability and/or functionality in the node 104.The MAC controllers 108 a and 108 b may be configured to implementEthernet protocols, such as those based on the IEEE 802.3 standard, forexample. Notwithstanding, the invention is not limited in this regard.

The MAC controller 108 a may communicate with the PHY device 110 a viaan interface 114 a and with the host 106 a via a bus controllerinterface 116 a. The MAC controller 108 b may communicate with the PHYdevice 110 b via an interface 114 b and with the host 106 b via a buscontroller interface 116 b. The interfaces 114 a and 114 b correspond toEthernet interfaces that comprise protocol and/or link managementcontrol signals. The interfaces 114 a and 114 b may be multi-ratecapable interfaces and/or media independent interfaces (MII). The buscontroller interfaces 116 a and 116 b may correspond to PCI or PCI-Xinterfaces. Notwithstanding, the invention is not limited in thisregard.

In operation, the amount of data generated by the node(s) 102 and/or 104during a given time interval may be significantly less than a maximumdata rate at which the nodes 102 and 104 may be enabled to communicateover the link 112. Consequently, continuously operating the link 112 atits maximum data rate may be inefficient in terms of energy consumptiondue, at least in part, to IDLE symbols being transmitted on the link forsignificant period of time and due to logic, circuitry, and/or code inthe node(s) 102 and/or 104 being continuously operated in a state tosupport the maximum data rate of the link. Thus, certain aspects of theinvention may enable improving the power efficiency of the network 100by duty cycling the data rate of the link 112 between two or more datarates to match the data rate at which traffic is being generated.

In some instances, data, such as multimedia streams, may inherently havea cyclic and/or periodic pattern. Accordingly, various aspects of theinvention may be enabled to duty cycle the data rate on the link 112 tomatch the pattern at which the multimedia traffic may be generated. Insome instances, data arriving at the MAC from higher layers may not beinherently bursty, but may be shaped via buffering, such that it may beconveyed to the physical layer in a cyclic or periodic pattern. In suchinstances, a resulting pattern of traffic out of the buffers may bedetermined, for example, by latency requirements of the data.Accordingly, the data rate on the link 112 may be duty cycled to matchthe pattern at which data is buffered and subsequently conveyed to thephysical layer. Thus, various logic, circuitry, and/or code within thenodes 102 and 104 may be operable to duty cycle a data rate of the link112 such that the time averaged data rate of the link 112 meets the timeaveraged rate at which data to be communicated over the link 112 isgenerated. In various embodiments of the invention, the trade offbetween energy utilized for buffering data and energy utilized fortransmitting data may be balanced so as to optimize power consumption ofthe nodes 102 and 104.

In an exemplary embodiment of the invention, the link 112 may beoperated at a maximum supported data rate for a portion of a timeinterval and may go to a zero data rate for a remaining portion of thetime interval. In another exemplary embodiment of the invention, thenodes 102 and 104 may communicate at a high(er) intermediate data ratefor a portion of a time interval and may go to a low(er) intermediatedata rate for a remaining portion of the time interval. In anotherexemplary embodiment of the invention, the nodes 102 and 104 maycommunicate at a maximum supported data rate for a portion of a timeinterval and may go to a low(er) intermediate data rate for a remainingportion of the time interval. In another exemplary embodiment of theinvention, the nodes 102 and 104 may communicate at a high(er)intermediate data rate for a portion of a time interval and may go tozero data rate for a remaining portion of the time interval. The datarate on the link 112 may be controlled via one or more exemplary methodscomprising: adjusting a number of active physical channels on the link112, adjusting a signal constellation utilized for representing data onthe link 112, reducing the number of PAM levels utilized for signalingon the link 112, adjusting the inter-frame gap (IFG), and adjusting asymbol rate on the link 112. Operating at a low(er) data rate may reducethe amount of energy consumed in generating and transmitting IDLEsymbols and may additionally enable various logic, circuitry, and/orcode in the nodes 102 and 104 to be disabled, slowed down, or otherwiseplaced into a low(er) power state.

To ensure reliable communications over the link 112, each of the nodes102 and 104 may need to adjust and/or monitor various parameters and/orcircuitry to account for variables such as the type of cabling overwhich data is being communicated and the environmental conditions (e.g.temperature) surrounding the cabling. This process may be referred to as“training” and may adapt a link partner to current link conditions suchthat reliable communications may be established on a link. For example,training may comprise configuring various parameters, circuitry, and ortiming loops in one or both of the nodes 102 and 104 such that the nodes102 and 104 may be synchronized and/or reliably communicate over one ormore physical channels of the link 112. In this manner, training mayensure reliable operation of functions such as echo cancellation,far-end crosstalk cancellation, and near-end crosstalk cancellation maybe performed. Accordingly, during time periods when no data may becommunicated over the link 112, a minimal amount of logic, circuitry,and/or code in the nodes 102 and 104 may be powered up (enabled) suchthat a minimal amount of energy and/or information may be exchangedbetween the nodes 102 and 104. This may eliminate a need for re-trainingupon transitioning back to the a high(er) or maximum data rate.

FIG. 2 is a block diagram illustrating an exemplary Ethernet overtwisted pair PHY device architecture comprising a multi-rate capablephysical layer block, in accordance with an embodiment of the invention.Referring to FIG. 2, there is shown a network node 200 which maycomprises an Ethernet over twisted pair PHY device 202, a MAC controller204, a host 206, an interface 208, and a bus controller interface 210.The PHY device 202 may be an integrated device which may comprise amulti-rate capable physical layer block 212, one or more transmitters214, one or more receivers 220, a memory 216, a memory interface 218,and one or more input/output interfaces 222.

The PHY device 202 may be an integrated device that comprises amulti-rate capable physical layer block 212, one or more transmitters214, one or more receivers 220, a memory 216, a memory interface 218,and one or more input/output interfaces 222. The operation of the PHYdevice 202 may be the same as or substantially similar to that of thePHY devices 110 a and 110 b disclosed in FIG. 1. In this regard, the PHYdevice 202 may provide layer 1 (physical layer) operability and/orfunctionality that enables communication with a remote PHY device.Similarly, the operation of the MAC controller 204, the host 206, theinterface 208, and the bus controller 210 may be the same as orsubstantially similar to the respective MAC controllers 108 a and 108 b,hosts 106 a and 106 b, interfaces 114 a and 114 b, and bus controllerinterfaces 116 a and 116 b as described in FIG. 1. The MAC controller204 may comprise a multi-rate capable interface 204 a that may comprisesuitable logic, circuitry, and/or code to enable communication with thePHY device 202 at a plurality of data rates via the interface 208.

The multi-rate capable physical layer block 212 in the PHY device 202may comprise suitable logic, circuitry, and/or code that may enableoperability and/or functionality of physical layer requirements. In thisregard, the multi-rate capable physical layer block 212 may enablegenerating the appropriate link discovery signaling utilized forestablishing communication with a remote PHY device in a remote networknode. The multi-rate capable physical layer block 212 may communicatewith the MAC controller 204 via the interface 208. In one aspect of theinvention, the interface 208 may be a media independent interface (MII)and may be configured to utilize a plurality of serial data lanes forreceiving data from the multi-rate capable physical layer block 212and/or for transmitting data to the multi-rate capable physical layerblock 212. The multi-rate capable physical layer block 212 may beconfigured to operate in one or more of a plurality of communicationmodes, where each communication mode may implement a differentcommunication protocol. These communication modes may include, but arenot limited to, Ethernet over twisted pair standards 10BASE-T,100BASE-TX, 1000BASE-T, 10GBASE-T, and other similar protocols thatutilize multiple physical channels between network nodes. The multi-ratecapable physical layer block 212 may be configured to operate in aparticular mode of operation upon initialization or during operation.For example, auto-negotiation may utilize the FLP bursts to establish arate (e.g. 10 Mbps, 100 Mbps, 1000 Mbps, or 10 Gbps) and mode(half-duplex or full-duplex) for transmitting information,

The multi-rate capable physical layer block 212 may be coupled to memory216 through the memory interface 218, which may be implemented as aserial interface or a bus. The memory 216 may comprise suitable logic,circuitry, and/or code that may enable storage or programming ofinformation that includes parameters and/or code that may effectuate theoperation of the multi-rate capable physical layer block 212. Theparameters may comprise configuration data and the code may compriseoperational code such as software and/or firmware, but the informationneed not be limited in this regard. Moreover, the parameters may includeadaptive filter and/or block coefficients for use, for example, by themulti-rate capable physical layer block 212 and/or the hybrids 226.

Each of the transmitters 214 a, 214 b, 214 c, 214 d may comprisesuitable logic, circuitry, and/or code that may enable transmission ofdata from the node 200 to a remote node via, for example, the link 112in FIG, 1. The receivers 220 a, 220 b, 220 c, 220 d may comprisesuitable logic, circuitry, and/or code that may enable receiving datafrom a remote node. Each of the transmitters 214 a, 214 b, 214 c, 214 dand receivers 220 a, 220 b, 220 c, 220 d in the PHY device 202 maycorrespond to a physical channel that may comprise the link 112. In thismanner, a transmitter/receiver pair may interface with each of thephysical channels 224 a, 224 b, 224 c, 224 d. In this regard, thetransmitter/receiver pairs may be enabled to provide the appropriatecommunication rate and mode for each physical channel.

The input/output interfaces 222 may comprise suitable logic circuitry,and/or code that may enable the PHY device 202 to impress signalinformation onto a physical channel, for example a twisted pair of thelink 112 disclosed in FIG. 1. Consequently, the input/output interfaces222 may, for example, provide conversion between differential andsingle-ended, balanced and unbalanced, signaling methods. In thisregard, the conversion may depend on the signaling method utilized bythe transmitter 214, the receiver 220, and the type of medium of thephysical channel. Accordingly, the input/output interfaces 222 maycomprise one or more baluns and/or transformers and may, for example,enable transmission over a twisted pair. Additionally, the input/outputinterfaces 222 may be internal or external to the PHY device 202. Inthis regard, if the PHY device 202 comprises an integrated circuit, then“internal” may, for example, refer to being “on-chip” and/or sharing thesame substrate. Similarly, if the PHY device 202 comprises one or morediscrete components, then “internal” may, for example, refer to being onthe same printed circuit board or being within a common physicalpackage.

The PHY device 202 may be enabled to transmit and receive simultaneouslyover up to four or more physical links. Accordingly, the node 200 maycomprise a number of hybrids 226 corresponding to the number of physicallinks. Each hybrid 226 may comprise suitable logic, circuitry, and/orcode that may enable separating transmitted and received signals from aphysical link. For example, the hybrids may comprise echo cancellers,far-end crosstalk (FEXT) cancellers, and/or near-end crosstalk (NEXT)cancellers. Each hybrid 226 in the node 300 may be communicativelycoupled to an input/output interface 222.

In operation, the node 200 may communicate with a remote node via thelink 112. For example, for 10 Gbps Ethernet, the node 200 may transmitdata to and receive data from a remote node via one or more of thephysical channels 224 a, 224 b, 224 c, and 224 d. In this regard, whenthere is no data for the node 200 to transmit, then it may transmit IDLEsymbols to keep itself and/or the remote partner “trained”. In thismanner, power consumption of a network may be largely independent of theamount of actual data being transmitted over the network. Accordingly,controlling the data rate over the link 112 may enable the node 200 totransmit fewer IDLE symbols and thus communicate in a more energyefficient manner. In this regard, the node 200 may transmit data overthe link 112 at different data rates during different portions of a timeinterval.

In various embodiments of the invention, the node 200 may disable, orput into a low(er) power state, one or more of the physical channels224, when those one or more physical channels are not required to meetcurrent and/or future demand of the link. In this manner, transmitters214, receivers 220, hybrids 226, and/or portions of the multi-ratecapable physical layer block 212 associated with the unused physicalchannels may be put into a low(er) power state. A physical channel notutilized to convey information and/or in a low(er) power state may bereferred to as inactive, while a physical channel utilized to conveyinformation and/or not in a low(er) power state may be referred to asactive, In various embodiments of the invention, a channel in a low(er)power state may convey little or no data, convey IDLE symbols, and/orconvey other energy. In some instances, aspects of the invention mayenable placing all channels of a link into a low(er) power state.

In various embodiments of the invention, a data rate of a communicationlink may be controlled by adjusting the size of a signal constellation.In this regard, a signal constellation utilized to transmit signals maybe reduced to provide lower data rates. For example, a subset of alarger signal constellation may be chosen such that encoding anddecoding signals may be less hardware and/or processor intensive. Inthis manner, portions of the multi-rate capable physical layer block 212may consume less energy when encoding data utilizing a smaller ordifferent signal constellation.

In various embodiments of the invention, a data rate of a communicationlink may be controlled by adjusting the PAM levels utilized forsignaling. For example, in instances such as 10 Gbps Ethernet, wheredata it typically encoded utilizing a PAM-16 scheme, aspects of theinvention may enable switching to PAM-8 or PAM-4 for lower data rates.In this regard, utilizing fewer PAM levels, and thus smaller voltages,may reduce power consumption in the system 200 as well as energyconsumed on the link 212.

In various embodiments of the invention, a data rate of a communicationlink may be controlled by controlling the inter-frame gap time orinter-packet gap (IPG) time. In this regard, increasing the IFG mayreduce the data rate while decreasing the IFG may increase the datarate.

FIG. 3A is a diagram illustrating duty cycling a data rate of a networklink between a zero data rate and a maximum supported data rate of thelink, in accordance with an embodiment of the invention. Referring toFIG. 3A, there is shown a graph 302 depicting data being generated and agraph 304 depicting a corresponding duty cycled data rate on anassociated link. The data may be generated in one or more nodes whichmay communicate over a common link, such as the nodes 102 and 104.Although FIG. 3A depicts the link 112 being duty cycled between two datarates, the invention is not limited in this regard and the link may beduty cycled utilizing three or more data rates. Additionally, althoughFIG. 3A depicts the data rate transitioning between data rates threetimes per time interval, the inventions is not so limited and maytransition between data rates any number of times during a timeinterval.

During the exemplary time interval t1, data to be communicated over thelink 112 may be generated at 25% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be zero for75% of time interval t1 and may be 100% of the maximum data rate for 25%of time interval t1.

During the exemplary time interval t2, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be zero for50% of time interval t2 and may be 100% of the maximum data rate for 50%of time interval t2.

During the exemplary time interval t3, data to be communicated over thelink 112 may be generated at 75% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be zero for25% of time interval t2 and may be 100% of the maximum data rate for 75%of time interval t3.

During the exemplary time interval t4, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be zero for50% of time interval t4 and may be 100% of the maximum data rate for 50%of time interval t4.

During the exemplary time interval t5, data to be communicated over thelink 112 may be generated at 25% of the maximum data rate supported bythe link 112. Accordingly, during time interval t5, the data rate of thelink 112 may be zero for 75% of time interval t5 and may be 100% of themaximum data rate for 25% of time interval t5.

FIG. 3B is a diagram illustrating duty cycling a data rate of a networklink between a zero data rate and an intermediate supported data rate ofthe link, in accordance with an embodiment of the invention. Referringto FIG. 3B, there is shown a graph 306 depicting data being generatedand a graph 308 depicting a corresponding duty cycled data rate on anassociated link. The data may be generated in one or more nodes whichmay communicate over a common link, such as the nodes 102 and 104.Although FIG. 3B depicts the link 112 being duty cycled between two datarates, the invention is not limited in this regard and the link may beduty cycled utilizing three or more data rates. Additionally, althoughFIG. 3B depicts the data rate transitioning between data rates threetimes per time interval, the inventions is not so limited and maytransition between data rates any number of times during a timeinterval.

The intermediate data rate may be determined based on the maximum rate,or maximum expected rate, at which data may be generated by nodescommunicatively coupled to the link. In the exemplary embodiment of theinvention depicted, the maximum rate at which data may be generated forcommunication over the link 112 may be 75%.

During the exemplary time interval t1, data to be communicated over thelink 112 may be generated at 25% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be zero for66⅓% of time interval t1 and may be 75% of the maximum data rate for33⅓% of time interval t1.

During the exemplary time intervals t2, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be zero for33⅓% of time interval t2 and may be 75% of the maximum data rate for66⅓% of time interval t2.

During the exemplary time interval t3, data to be communicated over thelink 112 may be generated at 75% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 75% ofthe maximum data rate for the duration of time interval t3.

During the exemplary time intervals t4, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, during time interval t4, the data rate of thelink 112 may be zero for 33⅓% of time interval t4 and may be 75% of themaximum data rate for 66⅓% of time interval t4.

During the exemplary time interval t5, data to be communicated over thelink 112 may be generated at 25% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be zero for66⅓% of time interval t5 and may be 75% of the maximum data rate for33⅓% of time interval t5.

FIG. 3C is a diagram illustrating duty cycling a data rate of a networklink between a first intermediate supported data rate of the link and asecond intermediate supported data rate of the link, in accordance withan embodiment of the invention. Referring to FIG. 3C, there is shown agraph 310 depicting data being generated and a graph 312 depicting acorresponding duty cycled data rate on an associated link. The data maybe generated in one or more nodes, which may communicate over a commonlink, such as the nodes 102 and 104. Although FIG. 3C depicts the link112 being duty cycled between two data rates, the invention is notlimited in this regard and the link may be duty cycled utilizing threeor more data rates. Additionally, although FIG. 3C depicts the data ratetransitioning between data rates three times per time interval, theinventions is not so limited and may transition between data rates anynumber of times during a time interval.

The first intermediate data rate may be determined based on the minimumrate, or minimum expected rate, at which data may be generated by nodescommunicatively coupled to the link 112. In the exemplary embodiment ofthe invention depicted in FIG. 3C, the minimum rate at which data may begenerated for communication over the link 112 may be 25%. Similarly, thesecond intermediate data rate may be determined based on the maximumrate at which data may be generated or expected to be generated by nodescommunicatively coupled to the link 112. In the exemplary embodiment ofthe invention depicted, the maximum rate at which data may be generatedfor communication over the link 112 may be 75%.

During the exemplary time interval t1, data to be communicated over thelink 112 may be generated at 25% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 25% ofthe maximum data rate for the duration of time interval t1.

During the exemplary time intervals t2, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 25% for50% of time interval t2 and may be 75% of the maximum data rate for 50%of time interval t2.

During the exemplary time interval t3, data to be communicated over thelink 112 may be generated at 75% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 75% forthe duration of time interval t3.

During the exemplary time intervals t4, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 25% for50% of time interval t4 and may be 75% of the maximum data rate for 50%of time interval t4.

During the exemplary time interval t5, data to be communicated over thelink 112 may be generated at 25% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 25% ofthe maximum data rate for the duration of time interval t5.

FIG. 3D is a diagram illustrating duty cycling a data rate of a networklink between an intermediate supported data rate of the link and amaximum supported data rate of the link, in accordance with anembodiment of the invention. Referring to FIG. 3D, there is shown agraph 314 depicting data being generated and a graph 316 depicting acorresponding duty cycled data rate on an associated link. The data maybe generated in one or more nodes which may communicate over a commonlink, such as the nodes 102 and 104. Although FIG. 3D depicts the link112 being duty cycled between two data rates, the invention is notlimited in this regard and the link may be duty cycled utilizing threeor more data rates. Additionally, although FIG. 3D depicts the data ratetransitioning between data rates three times per time interval, theinventions is not so limited and may transition between data rates anynumber of times during a time interval.

The intermediate data rate may be determined based on the minimum rate,or minimum expected rate, at which data may be generated by nodescommunicatively coupled to the link. In the exemplary embodiment of theinvention depicted in FIG. 3D, the minimum rate at which data may begenerated for communication over the link 112 may be 25%.

During time interval t1, data to be communicated over the link 112 maybe generated at 25% of the maximum data rate supported by the link 112.Accordingly, the data rate of the link 112 may be 25% of the maximumdata rate for the duration of time interval t1.

During the exemplary time interval t2, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, during time interval t2, the data rate of thelink 112 may be 25% of the maximum supported data rate for 66⅓% of timeinterval t2 and may be 100% of the maximum data rate for 33⅓% of timeinterval t2.

During the exemplary time interval t3, data to be communicated over thelink 112 may be generated at 75% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 25% ofthe maximum data rate for 33⅓% of time interval t3 and may be 100% ofthe maximum supported data rate for 66⅓% of time interval t3.

During the exemplary time interval t4, data to be communicated over thelink 112 may be generated at 50% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 25% ofthe maximum supported data rate for 66⅓% of time interval t4 and may be100% of the maximum data rate for 33⅓% of time interval t4.

During the exemplary time interval t5, data to be communicated over thelink 112 may be generated at 25% of the maximum data rate supported bythe link 112. Accordingly, the data rate of the link 112 may be 25% ofthe maximum data rate for the duration of time interval t5.

FIG. 3E is a diagram illustrating duty cycling a data rate of a networklink which carries traffic with varying latency sensitivities, inaccordance with an embodiment of the invention. Referring to FIG. 3there is shown a graph 318 depicting data being generated and a graph320 depicting a corresponding duty cycled data rate on an associatedlink. The data may be generated in one or more nodes which communicateover a common link, such as the nodes 102 and 104. The data may begenerated in one or more nodes which may communicate over a common link,such as the nodes 102 and 104

As illustrated in graph 318, the data generated for communication over anetwork link may comprise data, such as a multimedia stream, that may berelatively sensitive to latency and data, such as general web traffic,that may be relatively insensitive to latency. As illustrated in graph320, a first duty cycling, with period T1, may be utilized forcommunicating the latency sensitive traffic over a network link. Asillustrated in graph 322, a second duty cycling, with period T2, may beutilized for communicating the latency insensitive traffic over anetwork link. In this manner, the latency sensitive traffic may becommunicated in more frequent but shorter bursts whereas the latencyinsensitive traffic may be communicated in longer but less frequentbursts. Combining graphs 320 and 322 may thus result in graph 324illustrating the duty cycling of a data rate to communicate traffic withvarying latency tolerance over a common link.

FIG. 4 is a flow chart illustrating exemplary steps for duty cycling adata rate of a network link, in accordance with an embodiment of theinvention. Referring to FIG. 4, subsequent to start step 402 theexemplary steps may advance to step 404. In step 404, the nodes 102 and104 communicatively coupled via the network link 102 may each determinean amount and/or type of data being generated for communication over thelink 112. In this regard, the average data rate may be determined and/orpredicted based, for example, on past traffic statistics and/or programsrunning on the nodes. Subsequent to step 404, the exemplary steps mayadvance to step 406.

In step 406, the nodes 102 and 104, may determine a duty cycling periodbased on a variety of factors such as the type of data beingcommunicated on the link, a maximum data rate of the link, buffer sizes,and an amount of time it takes the nodes to transition between datarates. In this regard, controlling the data rates and the duty cycleperiod may enable achieving a wide range of average data rates withgreat resolution. For example, the average data rate over a timeinterval T1 may be determined as follows:

$\overset{\_}{D} = {{\frac{t_{1\; a}}{T\; 1}D_{1\; a}} + {\frac{t_{1\; b}}{T\; 1}D_{1\; b}}}$

where D is the average data rate of the link during the interval T1,D_(1a) is the data rate on the link during a first portion, t1 a, of thetime interval T1 and D1 b is the data rate on the link during aremaining portion, t1 b, of the time interval T1.

In step 408, it may be determined how to achieve the data ratesdetermined in step 406. In this regard, exemplary techniques forcontrolling the data rate may comprise one or more of adjusting a numberof active physical channels on the link 112, adjusting a signalconstellation utilized for representing data on the link 112, reducingthe number of PAM levels utilized for signaling on the link 112,adjusting the inter-frame gap (IFG), and adjusting a symbol rate on thelink 112. Subsequent to step 408, the exemplary steps may return to step404.

Exemplary aspects of a method and system for supporting a variable andenergy efficient data rate using a duty cycling technique and multiplepower states on an Ethernet link are provided. In various embodiments ofthe invention, a data rate on a network link 112 may be duty cycledbased on characteristics of data communicated over it such that data maybe communicated over the link at a first data rate for a first portionof a specified time interval and may be communicated over the link at asecond data rate for a second portion of the specified time interval.The duration of each portion of the time interval and/or the data rateduring each portion of the time interval may be adjusted to control theduty cycling. Exemplary characteristics may comprise an amount of, atype of, and/or an application associated with, the data communicatedover the network. The first data rate may be a zero data rate. Thesecond data rate may be a maximum data rate supported by the networklink. The data rate may be controlled by adjusting one or more of anumber of active physical channels in the network link, a signalconstellation utilized for representing data on the network link, anumber of pulse amplitude modulation levels utilized for signaling onthe network link, and one or more inter-frame gaps on the network link.Power consumed in a device connected to the network link may becontrolled based on the duty cycling of the link. In this regard,various components in the device may be powered up and/or down duringthe first and/or second portions of the time interval.

Another embodiment of the invention may provide a machine and/orcomputer readable storage and/or medium, having stored thereon, amachine code and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for supportinga variable and energy efficient data rate using a duty cycling techniqueand multiple power states on an Ethernet link.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

1. A method for networking, the method comprising: duty cycling, basedon characteristics of data communicated via a network link, a data rateon said network link such that said network link operates at a firstdata rate for a first portion of a specified time interval and saidnetwork link operates at a second data rate for a second portion of saidspecified time interval. 2-20. (canceled)